/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.trino.spooling.filesystem;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import com.google.common.hash.HashCode;
import com.google.common.hash.Hashing;
import com.google.inject.Inject;
import io.trino.filesystem.Location;

import java.util.List;

import static java.util.Objects.requireNonNull;

public class PartitionedFileSystemLayout
        extends SimpleFileSystemLayout
{
    private final int partitions;

    @Inject
    public PartitionedFileSystemLayout(PartitionedLayoutConfig layoutConfig)
    {
        this.partitions = requireNonNull(layoutConfig, "layoutConfig is null").getPartitions();
    }

    @Override
    public Location location(Location rootLocation, FileSystemSpooledSegmentHandle segmentHandle)
    {
        return super.location(rootLocation.appendPath(partition(segmentHandle)), segmentHandle);
    }

    @Override
    public List<Location> searchPaths(Location rootLocation)
    {
        ImmutableList.Builder<Location> builder = ImmutableList.builderWithExpectedSize(partitions);
        for (int i = 0; i < partitions; i++) {
            builder.add(rootLocation.appendPath(partition(i)));
        }
        return builder.build();
    }

    private String partition(FileSystemSpooledSegmentHandle handle)
    {
        HashCode hashCode = Hashing.murmur3_32_fixed().hashBytes(handle.uuid());
        return partition(Hashing.consistentHash(hashCode, partitions));
    }

    private String partition(int partition)
    {
        return Strings.padEnd(Integer.toString(partition), 3, '0') + "-spooled";
    }
}
